YAOSC (Yet Another Old School Clone)
Check this skill when you use an attack that strikes an area instead of a single point on a single target. This includes nets, siege weapons, cabers, and some spell effects, but not flasks of acid or flaming oil — those target points, and use a normal ranged attack roll. A successful check allows you to center the attack as you desire, within the attack’s range. Note that area attacks have range units and range penalties just as ranged weapon attacks do. You must possess an appropriate quirk or ability to effectively use some area attacks, including nets, spells, and siege engines.
A failure results in scattering. Roll two dice; a d12 for direction and d3 for distance. The direction die indicates the shot going long (12), short (6), or wide to the right (1-5) or left (7-11) as on the face of a clock. Halve the d3 result and multiply by the range unit of the attack; that is how far off-target the strike is.
Bob the Unready is manning a catapult with a skill of 4 and a range unit of 20 meters, firing at a target about 45 meters away, for a -1 range penalty. He rolls a 6, meaning the check has failed; the scatter results are 2 and 1, meaning the catapult stone strikes 10 meters away from the intended target, a little back and to the right (at the 2:00 position, or deviating 60º from the intended path).
Regardless of the success of the roll, anyone caught within the area of effect suffers the effects (although they may have a chance to save against it).